An energy attenuation device for a conduit conveying a liquid under pressure, a system incorporating same, and a method for attenuating energy in a conduit, are provided. The device includes a conduit, a restrictor disposed in the conduit and dividing the interior thereof into an inlet chamber and an outlet chamber, and a first tube disposed in one of the chambers, wherein an annular space is formed between the inner peripheral surface of the conduit and an outer peripheral surface of the tube. One end of the tube is connected to and in fluid communication with the restrictor or with the inlet or outlet end of the one chamber, and the other, free end of the tube is spaced by an open gap from the inlet or the outlet end of the one chamber or from the restrictor. The tube has at least one aperture in the free end and/or on the peripheral surface thereof for providing fluid communication between the tube and the one chamber.

Claim:

What is claimed is:

1. An energy attenuation device for a system conveying a liquid under pressure, said device comprising:

a conduit means having an inlet opening for receiving a liquid from said system, and an outlet opening for returning said liquid to said system;

a restrictor means disposed in said conduit means in such a way as to divide the interior of said conduit means into an inlet chamber having an inlet end and an outlet chamber having an outlet end, wherein said chambers are in fluid communicationwith one another via said restrictor means; and

a first tube disposed in one of said chambers, wherein the other of said chambers contains no tube, wherein an annular space is formed between an inner peripheral surface of said conduit means and an outer peripheral surface of said first tube,wherein said first tube has a first end connected to and in fluid communication with said restrictor means or with said inlet or outlet end of said one chamber, and a second, free end that is spaced by an open gap from said inlet or outlet end of saidone chamber or from said restrictor means, wherein said first tube has at least one aperture in said free end and/or on said peripheral surface thereof for providing fluid communication between said first tube and said one chamber.

2. An energy attenuation device according to claim 1, wherein said first tube is disposed in said outlet chamber, and wherein said first end of said first tube is connected to said restrictor means and said free end thereof is spaced from saidoutlet end of said outlet chamber.

3. An energy attenuation device according to claim 1, wherein said free end of said first tube is open to provide said aperture therein and said peripheral surface of said first tube has no apertures.

4. An energy attenuation device according to claim 1, wherein said peripheral surface of said first tube is provided with at least one aperture, and said free end of said first tube is open or closed off.

5. An energy attenuation device according to claim 1, wherein said other chamber that contains no tube has an effective length of from 1/2 inch to 24 inches.

6. An energy attenuation device for a system conveying a liquid under pressure, said device comprising:

a conduit means having an inlet opening for receiving a liquid from said system, and an outlet opening for returning said liquid to said system;

a restrictor means disposed in said conduit means in such a way as to divide the interior of said conduit means into an inlet chamber having an inlet end and an outlet chamber having an outlet end, wherein said chambers are in fluid communicationwith one another via said restrictor means;

a first tube disposed in one of said chambers, wherein an annular space is formed between an inner peripheral surface of said conduit means and an outer peripheral surface of said first tube, wherein said first tube has a first end connected toand in fluid communication with said restrictor means or with said inlet or outlet end of said one chamber, and a second, free end that is spaced by an open gap from said inlet or outlet end of said one chamber or from said restrictor means, and whereinsaid first tube has at least one aperture in said free end and/or on said peripheral surface thereof for providing fluid communication between said first tube and said one chamber; and

a further restrictor means disposed in said conduit means in such a way as to provide an intermediate chamber between said inlet and said outlet chambers, wherein successive ones of said chambers communicate with one another via the associatedrestrictor means, wherein said first tube is disposed in said inlet or said outlet chamber, wherein a second tube is disposed in one of said other chambers such that an annular space is formed between said inner peripheral surface of said conduit meansand an outer peripheral surface of said second tube, wherein said second tube has a first end connected to and in fluid communication with one of said restrictor means or with one end of said other chamber, and a second, free end that is spaced by anopen gap from said one end of said other chamber or from said restrictor means, and wherein said second tube has at least one aperture in said free end and/or on said peripheral surface thereof for providing fluid communication between said second tubeand said other chamber.

7. An energy attenuation device according to claim 6, wherein the ratio of the lengths of said first and second tubes ranges from 1:5 to 5:1.

8. An energy attenuation device according to claim 6, wherein either said outlet chamber or said inlet chamber contains no tube.

9. An energy attenuation device according to claim 8, wherein said first tube is disposed in said inlet chamber and said first end of said first tube is connected to said inlet end of said inlet chamber, and wherein said second tube is disposedin said intermediate chamber and said first end of said second tube is connected to said first-mentioned restrictor means.

10. An energy attenuation device according to claim 6, wherein said intermediate chamber contains no tube.

11. An energy attenuation device according to claim 10, wherein said first tube is disposed in said inlet chamber and said first end of said first tube is connected to said first-mentioned restrictor means, and wherein said second tube isdisposed in said outlet chamber and said first end of said second tube is connected to said further restrictor means.

12. An energy attenuation device according to claim 6, wherein said intermediate chamber is provided with a third tube that is connected at least one end thereof to one of said restrictor means.

13. An energy attenuation device according 6, wherein the ratio of the lengths of said first and second tubes ranges from 1:5 to 5:1, and wherein said intermediate chamber has an effective length of from 1/2 inch to 24 inches.

14. An energy attenuation device according to claim 6, wherein said free ends of said first and second tubes are open to provide said aperture therein, and said peripheral surfaces of said first and second tubes have no apertures.

15. An energy attenuation device according to claim 6, wherein said peripheral surface of at least one of said first and second tubes is provided with at least one aperture, and said free ends of said first and second tubes are open or closedoff.

16. An energy attenuation device for a system conveying a liquid under pressure, said device comprising:

a conduit means having an inlet opening for receiving a liquid from said system, and an outlet opening for returning said liquid to said system;

a restrictor means disposed in said conduit means in such a way as to divide the interior of said conduit means into an inlet chamber having an inlet end and an outlet chamber having an outlet end, wherein said chambers are in fluid communicationwith one another via said restrictor means;

a first tube disposed in said inlet chamber, wherein an annular space is formed between an inner peripheral surface of said conduit means and an outer peripheral surface of said first tube, wherein said first tube has a first end connected to andin fluid communication with said restrictor means or with said inlet end of said inlet chamber, and a second, free end that is spaced by an open gap from said inlet end of said inlet chamber or from said restrictor means, and wherein said first tube hasat least one aperture in said free end and/or on said peripheral surface thereof for providing fluid communication between said first tube and said inlet chamber;

a second tube disposed in said outlet chamber such that an annular space is formed between said inner peripheral surface of said conduit means and an outer peripheral surface of said second tube, wherein said second tube has a first end connectedto and in fluid communication with said restrictor means or with said outlet end of said chamber, and a second, free end that is spaced by an open gap from said outlet end of said outlet chamber or from said restrictor means, wherein said second tube hasat least one aperture in said free end and/or on said peripheral surface thereof for providing fluid communication between said second tube and said outlet chamber, and wherein said first and second tubes are made of polymeric material; and

at least one further separate attenuation device disposed in series with or parallel to said first mentioned energy attenuation device, wherein said further attenuation device comprises a further conduit means that contains no tube.

Description:

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a new energy attenuation device for a conduit that is adapted to convey liquid under pressure, as well as a system incorporating such a device and a method of attenuating energy in a conduit. The invention isparticularly suitable for placement in a conduit conveying liquid under pressure for the attenuation of pressure pulses in the liquid, especially in the hydraulic system of the power steering unit of a vehicle. The invention would also be suitable forother hydraulic fluids.

2. Prior Art Statement

In hydraulic systems where the operating liquid is circulated by a pump, the pulsations of pressure that are generated by the pump are transmitted through the conduits and result in noise and/or vibration being produced by the hydraulic liquid. In the case of power steering fluid in vehicles, such noise and/or vibration is caused, for example, when vehicles are being parked or unparked at idle or very low speeds of movement thereof, such as by barely moving into and out of a parking space orthe like while the wheels of the vehicle are being turned by the power steering mechanism thereof. In particular, substantial noise and/or vibration (shudder) can be produced in such a situation when the power steering fluid passes through the powersteering mechanism from the fluid pump to the effective steering structure. Further background into this area can be obtained from U.S. Pat. No. 3,323,305, Klees, whereby this U.S. Patent is being incorporated into this disclosure by this referencethereto.

Devices are known for suppressing noise in exhaust gas mufflers. For example, U.S. Pat. No. 4,501,341, Jones, provides two side branch resonators, while U.S. Pat. No. 4,371,053, Jones, provides for an apertured tube in a gas muffler housing. Systems are also known for controlling the resonation of pressure waves in fuel injection systems. For example, U.S. Pat. No. 5,168,855, Stone, passes fluid through check valves that are provided with a flow restriction either directly therein or in abypass line. U.S. Pat. No. 5,509,391, DeGroot, provides a spool valve assembly for controlling flow between inlet and outlet ports.

Applicants are not aware of any teaching of transferring flow of liquid under pressure from one tube to another as a means of suppressing energy, especially where at least one of the tubes is provided with at least one hole.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an improved device, system and method for attenuating energy in a conduit that conveys liquid under pressure.

This object is realized pursuant to the energy attenuation device of the present invention by providing a conduit means that is disposed in or is part of the liquid-conveying conduit, a restrictor disposed in the conduit and dividing the interiorthereof into an inlet chamber and an outlet chamber, and a first tube disposed in one of the chambers, wherein an annular space is formed between the inner peripheral surface of the conduit and an outer peripheral surface of the tube. One end of thetube is connected to and in fluid communication with the restrictor, and the other, free end of the tube is spaced by an open gap from the inlet end of the inlet chamber or the outlet end of the outlet chamber. The tube has at least one aperture in thefree end and/or on the peripheral surface thereof for providing fluid communication between the tube and the one chamber.

Accordingly, it is an object of this invention to provide a novel energy attenuation device having one or more of the novel features of this invention as set forth above or hereinafter shown or described.

Another object of this invention is to provide a new system incorporating such an energy attenuation device, such a system having one or more of the novel features of this invention as set forth above or hereinafter shown or described.

Another object of this invention is to provide a new method of attenuating energy in a conduit conveying liquid under pressure, such a method having one or more of the novel features of this invention as set forth above or hereinafter shown ordescribed.

Other objects, uses, and advantages of this invention are apparent from a reading of the specification in conjunction with the accompanying schematic drawings, which form a part thereof and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a simplified automotive power steering system that incorporates one exemplary embodiment of the energy attenuation device of this invention;

FIG. 2 is a cross-sectional view of one exemplary embodiment of the energy attenuation device of this invention;

FIG. 3 is a cross-sectional view of a second exemplary embodiment of the energy attenuation device of this invention;

FIG. 4 is a cross-sectional view of a third exemplary embodiment of the energy attenuation device of this invention;

FIGS. 5, 5a and 5b are enlarged cross-sectional views of a restrictor for use with an energy attenuation device of this invention;

FIG. 6 is a view similar to that of FIG. 2 of a modified energy attenuation device of this invention;

FIG. 7 is a cross-sectional view of a fourth exemplary embodiment of the energy attenuation device of this invention;

FIG. 8 is a cross-sectional view of a fifth exemplary embodiment of the energy attenuation device of this invention;

FIG. 8a shows a modification of the embodiment of FIG. 8;

FIG. 9 is a view similar to that of FIG. 4 of a modified energy attenuation device of this invention;

FIG. 10 is a cross-sectional view of a sixth exemplary embodiment of the energy attenuation device of this invention;

FIG. 10a shows a modification of the embodiment of FIG. 10;

FIG. 10b to 10g are cross-sectional views taken through the hose means and the tubes;

FIG. 11 is a modification of the embodiment of FIG. 10;

FIG. 12 is a cross-sectional view of a further exemplary embodiment of the energy attenuation device of this invention;

FIGS. 13 and 14 show various embodiments of tuning cable or tube arrangements for use in conjunction with the energy attenuation apparatus of this invention; and

FIG. 15 is a partial block diagram showing one arrangement for use in conjunction with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

While the various features of this invention are hereinafter illustrated and described as providing an energy or sound attenuation device for an automotive power steering system, it is to be understood that the various features of this inventioncan be utilized singly or in various combinations thereof to provide an energy attenuation device for other systems that convey liquid, especially liquid under pressure.

Therefore, this invention is not to be limited to only the embodiment illustrated in the drawings, because the drawings are merely utilized to illustrate one of the wide variety of usages of this invention.

Referring now to the drawings in detail, FIG. 1 illustrates a simplified automotive power steering system. During operation, the power steering pump 11 generates pressure ripples that are transmitted through tubing T, such as steel tubing, tothe pressure hose assembly or pressure line 12, the power steering gear 13, the return hose assembly or return line 14, and the reservoir 15, and finally flow back to the pump 11 itself by means of the supply line 16. It should be noted that rather thanbeing separated by a hose or similar conduit, the reservoir 15 and the pump 11 could actually be a single unit.

In order to greatly reduce noise, such as from resonance, for example in the pressure line 12 or in the return line 14, and thereby eliminate or at least greatly reduce the power steering noise or vibration generated by the power steering pump11, the energy attenuation device of this invention, which is indicated generally by the reference numeral 20, is disposed either in the pressure line 12, between the steering pump 11 and the gear 13, or in the return line 14, between the gear 13 and thereservoir 15 or the pump 11. In addition, it would also be conceivable to dispose the energy attenuation device 20 in both the pressure line 12 and the return line 14. Various exemplary embodiments of the energy attenuation device 20, and componentsand arrangements thereof, are illustrated in FIGS. 2-15 and will be described in detail subsequently.

The energy attenuation device 20 of this invention can, as indicated previously, be disposed in the pressure line 12 and/or the return line 14 of the system of FIG. 1. However, as illustrated in the exemplary embodiments of FIGS. 2-4 and 6-12,the energy attenuation device 20 can also be disposed in a separate hose section that is in turn disposed in such pressure line 12 or return line 14.

As can be seen from the embodiment of the energy attenuation device 20 illustrated in FIG. 2, two separate apertured tubes 21 are disposed in the chamber 22 formed in the hose section or means 23. In particular, an inlet tube 21a is connected tothe inlet end 25 of the chamber 22, whereas an outlet tube 21b is connected to the outlet end 26 of the chamber 22. The tubes 21a, 21b are disposed in the chamber 22 in such a way that not only are the free ends 27 and 28 thereof spaced from one anotherby an open gap, but the outer peripheral surfaces 30,31 of the inlet and outlet tubes 21a and 21b are spaced from the inner peripheral surface 32 of the hose or conduit means 23 in such a way that an annular space 33 is respectively provided about theouter peripheral surfaces 30,31 of each of the tubes 21a, 21b. By means of at least one, preferably several, holes 34 provided in each of the outer peripheral surfaces 30, 31 of the inlet and outlet tubes 21a, 21b, liquid entering the hose means 23 viathe tubing T can exit the inlet tube 21a into first the annular space 33 and then part of the remainder of the chamber 22, from where it can flow through further holes 34 into the outlet tube 21b and from there out of the hose means 23 into theright-hand tubing T. Depending upon whether the free ends 27, 28 of the tubes 21a, 21b are opened or closed, all or only part of the liquid in the pressure line 12 or return line 14 will pass through the holes 34 out of the inlet tube 21a and into theoutlet tube 21b. Details concerning the open or closed state of the free ends 27, 28 of the tubes 21a, 21b will be discussed subsequently.

In the embodiment of the energy attenuation device 20 illustrated in FIG. 2 the hose section 23, which is made of rubber or other elastomeric material, is disposed in the pressure line 12 or the return line 14 and is connected to the tubing T, ina fluid conveying manner, via respective couplings 36.

As indicated previously, the free ends 27, 28 of the inlet tube 21a and outlet tube 21b can be either open or closed off. Several possibilities exist for configuring the free ends 27 and 28. For example, both free ends could be open, or bothcould be closed. In addition, the free end 27 of the inlet tube 21a could be open while the free end 28 of the outlet tube 21b could be closed. On the other hand, the opposite arrangement could also be provided whereby the free end 27 of the inlet tube21a would be closed and the free end 28 of the outlet tube 21b would be open.

Although the embodiment illustrated in FIG. 2 provides for a single chamber 22 with the free ends 27, 28 of the inlet and outlet tubes 21a, 21b facing each other at the middle of the hose mixing region of the chamber 22, it has been foundaccording to the teachings of this invention that other configurations are also possible. For example, reference is now made to FIG. 3, wherein another configuration of the energy attenuation device of this invention is shown and is indicated generallyby the reference numeral 20A, wherein parts thereof similar to the energy attenuation device 20 of FIG. 2 are indicated by like reference numerals that where appropriate are followed by the reference letter A.

The embodiment of the energy attenuation device 20A illustrated in FIG. 3 differs from that shown in FIG. 2 in that the chamber 22A is divided by a restrictor 38 into an inlet chamber portion 39 and an outlet chamber portion 40. An enlarged viewof the restrictor 38 is shown in FIGS. 5-5b; the inner diameter of the restrictor is less than the inner diameter of the hose means 23A. It should be noted that the restrictor 38 is disposed in the hose means 23A, for example by crimping, in such a waythat communication between the chamber portions 39 and 40 can be only via the passage means, i.e. the reduced diameter portion, of the restrictor. The free end 27 of the inlet tube 21a is spaced from the restrictor 38 in the inlet chamber portion 39,while the free end 28 of the outlet tube 21b is spaced from the restrictor 38 in the outlet chamber portion 40. Thus, with the energy attenuation device 20A, liquid that is exiting the inlet tube 21a, either entirely or at least partially via the holes34, will enter the inlet chamber portion 39, will then flow through the reduced diameter portion of the restrictor 38, will enter the outlet chamber portion 40, and then at least partially via the holes 34 will enter the outlet tube 21b. As discussed inconjunction with the energy attenuation device 20 of FIG. 2, the free ends 27, 28 of the inlet and outlet tubes 21a, 21b can be either both open, both closed, or only one open and the other closed.

In the embodiment of the energy attenuation device 20A the inlet and outlet tubes 21a, 21b are connected to the inlet and outlet ends 25, 26 of the respective inlet chamber portion 39 or outlet chamber portion 40. However, it would also bepossible to connect the inlet and outlet tubes 21a, 21b directly to the restrictor 38 instead of to the inlet and outlet ends of the chamber. For example, reference is now made to FIG. 4, wherein another energy attenuation device of the presentinvention is shown and is indicated generally by the reference numeral 20B.

In the embodiment of the energy attenuation device 20B, the free ends 27, 28 of the inlet and outlet tubes 21a, 21b face away from one another, namely toward the inlet and outlet ends of the inlet chamber portion 39 and outlet chamber portion 40respectively, and are spaced from such inlet and outlet ends. Again, the free ends 27, 28 of the inlet and outlet tubes 21a, 21b can both be opened, can both be closed, or only one can be opened with the other being closed.

As indicated above, the two separate apertured tubes 21a, 21b are each provided with at least one hole 34 in the outer peripheral surface thereof. Pursuant to some presently preferred embodiments, it is contemplated that each of the aperturedtubes 21 will have a plurality of such holes 34. Several arrangements of these holes 34 are possible. For example, the holes 34 can be arranged in a longitudinal direction in one or more rows of such holes, either aligned or offset relative to oneanother, or can also be disposed in a random manner about the peripheral surfaces 30, 31 of the tubes 21a, 21b. FIG. 6 shows one such possible arrangement. In this embodiment, the apertured tube 21a on the inlet side has two holes 34 disposed180.degree. from one another. In contrast, the apertured tube 21b on the outlet side has two rows of four holes 34, with the rows being disposed 90.degree. from one another, and with the holes of one row being offset in a longitudinal direction fromthe holes of the other row. In addition, the free end of the tube 21a is open while the free end of the tube 21b is closed. It is to be understood that although the arrangement of FIG. 6 has been illustrated in conjunction with a tube arrangementsimilar to that of FIG. 2, such an arrangement of the holes 34 would be possible for any of the embodiments previously described.

In addition to the number and arrangement of the holes 34 in the apertured tubes 21, it will be appreciated that other system parameters will affect the noise attenuation that can be achieved. For example, the ratios and dimensions of thecomponents of the device relative to another can be varied. Although in the illustrated embodiments the lengths of the inlet and outlet tubes 21a, 21b are shown as being the same, the lengths of these two tubes can also differ from one another. Inaddition, the inlet and outlet tubes 21a, 21b can extend over varying proportions of the chamber 22. In the embodiment of the energy attenuation device 20 shown in FIG. 2, it is presently contemplated that each of the apertured tubes 21 will extend overmore that one fourth of the length of the chamber 22 of the hose means 23. Similarly, in the embodiments of FIGS. 3 and 4, it is contemplated that each of the apertured tubes 21a, 21b will extend over more than one half of the length of its respectiveinlet or outlet chamber portion 39 or 40.

Although the previously illustrated embodiments provide for an inlet tube 21a and an outlet tube 21b that are both provided with holes 34, it has been found according to the teachings of this invention that only one of the tubes 21a, 21b need beprovided with such holes. In addition, rather than providing a fairly wide space in the chamber 22 of the hose means 23 between the free ends 27, 28 of the inlet and outlet tubes 21a, 21b, a narrow gap could also be provided between such free ends. Forexample, reference is now made to FIG. 7, wherein another energy attenuation device of the present invention is shown and is indicated generally by the reference numeral 20C.

In the embodiment of the energy attenuation device 20C, the free ends 27, 28 of the inlet and outlet tubes 21a, 21b are separated from one another by only a narrow gap 42, for example a gap having a width of approximately 1/32-1/8 of an inch. Inaddition, only one of the tubes, namely the inlet tube 21a, is provided with holes 34, for example two such holes that are disposed 90.degree. or 180.degree. from one another. The narrow gap 42 between the free ends 27, 28 of the inlet and outlettubes 21a, 21b has in this embodiment been illustrated as being displaced toward the outlet end of the chamber 22C. However, such narrow gap could also be disposed closer to the inlet end of the chamber 22C, in which case the outlet tube 21b would belonger than the inlet tube 21a. Furthermore, although the holes 34 have been illustrated as being disposed approximately half way between the inlet and outlet ends of the chamber 22c, such holes 34 could be disposed at any desired location along one ofthe inlet or outlet tubes 21a, 21b. In addition, rather than being disposed on the inlet tube 21a, such holes 34 could also be disposed on the outlet tube 21b. Furthermore, any desired arrangement of the holes 34 is possible, and the embodiment of FIG.2 could also be modified to include the narrow gap 42 of the embodiment of FIG. 7, wherein both the inlet tube 21a and the outlet tube 21b could again be provided with holes 34.

In the embodiment of the energy attenuation device 20B illustrated in FIG. 4, a respective tube is disposed in each of the inlet and outlet chamber portions 39, 40. However, it has been found according to the teachings of this invention thatonly one of the chamber portions need contain a tube. For example, reference is now made to FIG. 8, wherein another energy attenuation device of the present invention is shown and is indicated generally by the reference numeral 20D.

In the embodiment of the energy attenuation device 20D, only one of the chambers contains a tube, with the other chamber being empty. In the illustrated embodiment, it is the inlet chamber portion 39 that contains no tube, and therefore formsthe empty chamber 55, while the outlet chamber portion 40 contains a tube, namely the outlet tube 21b, which is illustrated as being connected to the restrictor 38 and having its free end 28 spaced from the outlet end of the chamber 40. The outlet tube21b could also be connected to the outlet end of the chamber 40 and have its free end spaced from the restrictor 38. To provide fluid communication from the inlet chamber portion 39, i.e. the empty chamber 55, via the restrictor 38 to the outlet chamber40, the outlet tube 21b is provided with at least one aperture. For example, the free end 28 of the outlet tube 21b could be open, while the peripheral surface of the tube 21b could be provided with no apertures. Alternatively, the peripheral surfaceof the tube 21b could be provided with at least one hole (see FIG. 8a), and the free end 28 of the tube could be open or closed off.

Rather than the inlet chamber portion 39 being empty, the empty chamber 55 could be formed by the outlet chamber portion 40, with the chamber 39 then being provided with the inlet tube 21a, which could be connected to the inlet end of the chamber39 or to the restrictor 38. The empty chamber 55 could have a length of from 1/2 inch to 12 inches or even greater, and in one specific embodiment has a length of 140 mm, with the tube, for example the outlet tube 21b, having a length of 100 mm in achamber portion that has a length of 140 mm.

In the embodiment of the energy attenuation device 20B of FIG. 4, the inlet and outlet tubes 21a, 21b are provided with holes on the peripheral surfaces thereof. However, it has been found according to the teachings of this invention that itwould be possible to provide no holes on the peripheral surfaces of the inlet and outlet tubes and to have only the free ends of these tubes open. For example, reference is now made to FIG. 9, wherein another energy attenuation device of the presentinvention is shown and is indicated generally by the reference numeral 20E.

In the embodiment of the energy attenuation device 20E, the free ends 27, 28 of the inlet and outlet tubes 21a, 21b are open, while the peripheral surfaces of these tubes are not provided with any holes. In the illustrated embodiment, both theinlet and outlet tubes 21a, 21b are connected to the restrictor 38. However, it would also be possible to connect the inlet and outlet tubes to the inlet and outlet openings of their respective chambers, with the free ends of these tubes then beingspaced from the restrictor 38, similar to the embodiment illustrated in FIG. 3. Again however only the free ends would be open while the peripheral surfaces of the inlet and outlet tubes 21a, 21b would have no holes.

The ratio of the length of the inlet tube 21a to the length of the outlet tube 21b could range from 1:5 to 5:1, and in one specific embodiment of the present invention both have the same length of 154 mm, with both the inlet and outlet chamberportions having a length of 194 mm.

In this embodiment, the inlet and outlet tubes 21a, 21b are made of polymeric material.

Although in the previous embodiments the energy attenuation devices have been illustrated as being provided with at most two chambers, it has been found according to the teachings of this invention that the hose or conduit means could be providedwith three chambers. For example, reference is now made to FIG. 10 and FIG. 11, wherein other energy attenuation devices of the present invention are shown and are indicated generally by the reference numerals 20F and 20G.

In the embodiment of the energy attenuation device 20F, a further restrictor 57 is provided such that an intermediate chamber 58 that contains no tubes, in other words an empty chamber, is formed between the inlet and outlet chamber portions39,40. Although in the illustrated embodiment the inlet and outlet tubes 21a, 21b are connected directly to the restrictors 38, 57, with the free ends 27, 28 thereof being spaced from the inlet and outlet portions of the respective inlet and outletchamber portions 39, 40, it would also be possible to connect the inlet and outlet tubes 21a, 21b directly to the inlet and outlet portions of their respective chambers, with the free ends of the tubes then being spaced from the respective restrictors38, 57.

In addition, the free ends 27, 28 of the inlet and outlet tubes 21a, 21b could be open, while the peripheral surfaces of the tubes could be provided with no holes. Alternatively, the peripheral surface of at least one of the inlet and outlettubes 21a, 21b could be provided with holes (see FIG. 10a) while the free ends of the tubes could be open or closed off.

Rather than the third, empty chamber 58 being provided between the inlet and outlet chamber portions 39, 40, the empty chamber 58 could also be disposed after the second chamber, as indicated in the embodiment of the energy attenuation device 20Gillustrated in FIG. 11, or could even be disposed prior to the chamber 39. Again, the tubes 21a, 21b could be connected directly to the restrictors 38, 57, or to the inlet and outlet portions of their respective chambers.

The ratio of the length of the inlet tube 21a to the length of the outlet tube 21b could range from 1:5 to 5:1 or even greater. The empty, for example intermediate, chamber 58 has an effective length of from 1/2 inch to 24 inches or evengreater. In one specific embodiment of the present invention, the intermediate chamber 58 has a length of 200 mm, and the inlet and outlet tubes 21a, 21b both have the same length of 115 mm, with both the inlet and outlet chamber portions having alength of 155 mm.

The restrictors 38, 57 can, for example, have a length of from 41 to 46 mm.

The hose means 23 can be a single section of rubber and/or other elastomeric or plastic material that is connected to metal, especially stainless steel, tubing T by means of the couplings 36, or the hose means can also comprise two separate hosesections that are interconnected by the restrictor means 38. Furthermore, the hose means 23 may be made of a single layer or of a plurality of layers of the aforementioned rubber and/or plastic. The hose means 23 may also be suitably reinforced towithstand comparatively high fluid pressures. The hose means 23 could furthermore be made of metal, such as stainless steel. In addition, although the tubes 21 have been illustrated as being disposed in the hose means 23, such hose or conduit means canactually be a continuation of the tubing T, or a separate tubing section, again made of metal. In contrast, the tubes 21 can be made of polymeric material, especially tetrafluoroethylene fluorocarbon resins, fluorinated ethylene-propylene resins, orpolyamide; the apertured and/or open tubes could also be made of metal, especially stainless steel, or rubber. Thus, the tubes 21 can be either flexible or rigid. For the sake of convenience, the cross-sectional views of FIGS. 10b to 10g through thehose means and the tubes to show the various material possibilities therefor have been taken in conjunction with thej embodiment of FIG. 10. It is, however, to be understood that these views apply to the other illustrated and described embodiments aswell. Where the conduit means is a hose of rubber, other elastomeric material, or metal, it can, for example, have an inner diameter of 3/8 inch to 1/2 inch or larger. The diameter of the inlet and outlet tubes 21a, 21b will depend largely upon thediameter of the conduit means 23. For example, if the conduit means has an inner diameter of 3/8 inches, the inlet and outlet tubes could have an outer diameter of 5/16 inches or less. Similarly, if the conduit means has an inner diameter of 1/2inches, the inlet and outlet tubes could have an outer diameter of 3/8 inches or less. The length of the conduit means, and hence of the inlet and outlet tubes, can vary depending upon need and available space. By way of example only, the conduit meanscould have a length of 8 inches.

The size and shape of the holes 34 can also vary. For example, circular holes 34 can have a diameter of 1/16 inches, 1/8 inches, etc. If the holes 34 have an oval shape, pursuant to one specific embodiment of the present invention the dimensionof such holes can be 1/8 inches in width by 1/2 inches in length.

The restrictor means 38,55 has an inner diameter that is less than the inner diameter of the hose means 23. In addition, the inner diameter of the restrictor 38, 55 can be equal to, greater than or less than the inner diameter of the inlet andoutlet tubes. The restrictor means can be made of any suitable material, including metal, rubber and polymeric material (see FIGS. 5a and 5b).

The inventive energy attenuation device can also be used in conjunction with a variety of other sound and vibration attenuation devices, which are then also disposed in the pressure line 12 and/or return line 14. For example, a 1/4 wave cabletuning assembly can be provided, for example by disposing a steel cable in a further hose section. Examples of such tuning cable arrangements in further hose sections are shown in FIGS. 13 and 14, wherein FIG. 13 shows a single tuning cable 44 disposedin the further hose section or conduit means 45, whereas FIG. 14 shows two separate tuning cables 44 disposed in a further hose section or conduit means 46. An example of a known tuning cable is disclosed in the aforementioned patent to Klees, U.S. Pat. No. 5,323,305, which patent has been incorporated into this disclosure. The tuning cable arrangements in the conduit means 45 or 46 can be disposed in series with the inventive energy attenuation device, or can be disposed in parallel therewith. Other sound and vibration attenuation devices are also known. For example, reference is made to U.S. Pat. No. 4,611,633 (Buchholz et al), U.S. Pat. No. 5,172,729 (Vantelini) and U.S Pat. No. 5,201,343 (Zimmermann et al) whereby such US patents arealso being incorporated into this disclosure by this reference thereto. Furthermore, a spring-type energy attenuation device as disclosed in applicants copending U.S. patent application Ser. No. 08/853,770 could also be provided, whereby thedisclosure of such application is also incorporated into this disclosure by this reference thereto. One or more of such other attenuation devices could also be used in conjunction with the energy attenuation device 20-20H of the present invention. Forexample, FIG. 15 shows an arrangement where the tubing T is split into branches 48, each of which leads to an energy attenuation device that is schematically indicated by one of the boxes 50 or 51. This parallel arrangement can either be disposed inseries with one of the inventive energy attenuation devices 20-20H, or one of the boxes 50, 51 can contain an inventive energy attenuation device while the other box contains a known attenuation device. Furthermore, both boxes 50 and 51 can contain thesame or different ones of the inventive energy attenuation device 20-20H. It should be noted that two or more of the inventive energy attenuation devices could be disposed in series and/or in parallel with one another, or even with an empty hosesection. For example, reference is now made to FIG. 12, which illustrates another energy attenuation device 20H of the present invention. This embodiment shows an empty hose section 60 in series with one of the other inventive embodiments previouslydescribed, such as, by way of example, the embodiment 20D of FIG.8. The empty hose section 60 could also be disposed upstream of the other inventive embodiment, or even in parallel therewith.

In view of the foregoing, it can be seen that this invention not only provides a new energy attenuation device, but also this invention provides a new method for attenuating energy in a fluid conveying system.

While the forms and methods of this invention is now preferred have been illustrated and described as required by the Patent Statute, it is to be understood that other forms and method steps can be utilized and still fall within the scope of theappended claims, whereby it is believed that each claim sets forth a novel, useful and unobvious invention within the purview of the Patent Statute.